Add cppcheck target.
Add cppcheck target.

carnager/rofi,ThomasAdam/rofi,daemonl/rofi,jreinert/rofi,stettberger/rofi,jubalh/rofi,carnager/rofi,t-wissmann/rofi,jreinert/rofi,carnager/rofi,eigengrau/rofi,daemonl/rofi,eigengrau/rofi,ThomasAdam/rofi,jubalh/rofi,stettberger/rofi,t-wissmann/rofi